The proposed research will continue a systematic investigation into the role of metabolic conpartmentation in the regulation of biochemical differentiation in the cellular slime mold, Dictyostelium discoideum. Current efforts will be concerned with defining those regulatory mechanisms which control the rate of synthesis of a major developmental product in this system (i.e., the disaccharide trehalose) and its subsequent compartmentation at the cellular organelle and microenvironmental levels. The specific aims to be achieved will be: (1) to purify and characterize the biosynthetic enzyme involved in trehalose synthesis, i.e., trehalose-6-P (T6P synthetase; (2) to compare the effects of the polysaccharide, heparin on the catalytic properties and the state of aggregation of T6P synthetase with those elicited by the purified Dictyostelium acid mucopolysaccharide; (3) to obtain antibody specific for T6P synthetase and to quantitate via immunological methods the level of this enzyme in vitro during development and (4) to localize intracellular T6P synthetase during development by application of the techniques of immunoferritin and indirect immunofluorescent staining using purified antibody elicited against this enzyme.